{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,8]],"date-time":"2026-02-08T01:17:25Z","timestamp":1770513445653,"version":"3.49.0"},"reference-count":53,"publisher":"American Physiological Society","issue":"4","funder":[{"name":"Noregian University of Science and Technology"},{"DOI":"10.13039\/501100004590","name":"Helse Midt-Norge (Central Norway Regional Health Authority)","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100004590","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Applied Physiology"],"published-print":{"date-parts":[[2017,4,1]]},"abstract":"<jats:p> The vascular strain is very high during heavy handgrip exercise, but the intensity and kinetics to reach peak blood flow, and peak oxygen uptake, are uncertain. We included 9 young (25 \u00b1 2 yr) healthy males to evaluate blood flow and oxygen uptake responses during continuous dynamic handgrip exercise with increasing intensity. Blood flow was measured using Doppler-ultrasound, and venous blood was drawn from a deep forearm vein to determine arteriovenous oxygen difference (a-vO<jats:sub>2diff<\/jats:sub>) during 6-min bouts of 60, 80, and 100% of maximal work rate (WR<jats:sub>max<\/jats:sub>), respectively. Blood flow and oxygen uptake increased ( P &lt; 0.05) from 60%WR<jats:sub>max<\/jats:sub> [557 \u00b1 177(SD) ml\/min; 56.0 \u00b1 21.6 ml\/min] to 80%WR<jats:sub>max<\/jats:sub> (679 \u00b1 190 ml\/min; 70.6 \u00b1 24.8 ml\/min), but no change was seen from 80%WR<jats:sub>max<\/jats:sub> to 100%WR<jats:sub>max<\/jats:sub>. Blood velocity (49.5 \u00b1 11.5 to 58.1 \u00b1 11.6 cm\/s) and brachial diameter (0.49 \u00b1 0.05 to 0.50 \u00b1 0.06 cm) showed concomitant increases ( P &lt; 0.05) with blood flow from 60% to 80%WR<jats:sub>max,<\/jats:sub> whereas no differences were observed in a-vO<jats:sub>2diff<\/jats:sub>. Shear rate also increased ( P &lt; 0.05) from 60% (822 \u00b1 196 s<jats:sup>\u22121<\/jats:sup>) to 80% (951 \u00b1 234 s<jats:sup>\u22121<\/jats:sup>) of WR<jats:sub>max<\/jats:sub>. The mean response time (MRT) was slower ( P &lt; 0.05) for blood flow (60%WR<jats:sub>max<\/jats:sub> 50 \u00b1 22 s; 80%WR<jats:sub>max<\/jats:sub> 51 \u00b1 20 s; 100%WR<jats:sub>max<\/jats:sub> 51 \u00b1 23 s) than a-vO<jats:sub>2diff<\/jats:sub> (60%WR<jats:sub>max<\/jats:sub> 29 \u00b1 9 s; 80%WR<jats:sub>max<\/jats:sub> 29 \u00b1 5 s; 100%WR<jats:sub>max<\/jats:sub> 20 \u00b1 5 s), but not different from oxygen uptake (60%WR<jats:sub>max<\/jats:sub> 44 \u00b1 25 s; 80%WR<jats:sub>max<\/jats:sub> 43 \u00b1 14 s; 100%WR<jats:sub>max<\/jats:sub> 41 \u00b1 32 s). No differences were observed in MRT for blood flow or oxygen uptake with increased exercise intensity. In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WR<jats:sub>max<\/jats:sub> and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations. <\/jats:p><jats:p> NEW &amp; NOTEWORTHY This study evaluated blood flow regulation and oxygen uptake during small muscle mass forearm exercise with high to maximal intensity. Despite utilizing only a fraction of cardiac output, blood flow reached a plateau at 80% of maximal work rate and regulated peak oxygen uptake. Furthermore, the results revealed that muscle contractions dictated bulk oxygen delivery and yielded three times higher peak blood flow in the relaxation phase compared with mean values. <\/jats:p>","DOI":"10.1152\/japplphysiol.00983.2016","type":"journal-article","created":{"date-parts":[[2017,1,5]],"date-time":"2017-01-05T22:00:32Z","timestamp":1483653632000},"page":"907-917","source":"Crossref","is-referenced-by-count":27,"title":["Blood flow regulation and oxygen uptake during high-intensity forearm exercise"],"prefix":"10.1152","volume":"122","author":[{"given":"S. K.","family":"Nyberg","sequence":"first","affiliation":[{"name":"Department of Circulation and Medical Imaging, Faculty of Medicine, the Norwegian University of Science and Technology, Trondheim, Norway;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"O. 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